Deployment dynamics analysis of CALLISTO’s approach and landing system

Prior to landing of reusable space transportation systems, the vehicle’s landing legs needs to be fully deployed to enable a safe landing and further re-use of the space vehicle. During that phase the deployment system has to overcome harsh and challenging environmental conditions. In this study, a numerical simulator is developed in order to investigate these influences on the landing leg deployment dynamics. By means of an extensive aerodynamic database and a broad approach flight domain, the influence of aerodynamics, exhaust plume, and vehicle’s attitude on the deployment dynamics is analyzed. This study shows on the example of the first stage demonstrator CALLISTO (Cooperative Action Leading to Launcher Innovation in Stage Toss back Operations), that thrust level, vehicle attitude, and the deployment system parameters affect the deployment performance.

Computation on Infrared Radiation of Side Exhaust Plume under Spraying Water

The high temperature plume of ships has obvious infrared radiation feature. Spraying water-liquid droplets in side exhaust system can effectively reduce the high temperature of the tail gas to reduce the infrared radiation of the exhaust plume. In this paper, ANSYS Fluent is used to establish the concentration field and temperature field of the side exhaust plume atter spraying water-liquid droplets. And the statistic narrow band model (Malkmus model) and the C-G approximation method are used to calculate the infrared radiation intensity of the exhaust plume in the normal direction of the exhaust outlet from 3 to 5 μm on this basis. The final results show that spraying water-liquid droplets in side exhaust pipe can reduce the infrared radiation of the side exhaust plume from 3 to 5um by 88.9%% compared with the initial intensity; when the water flow reaches 0.7kg/s, infrared radiation intensity remains unchanged.

Numerical evaluation of the exhaust-direction effects on plume flow and helicopter infrared radiation under hover and cruise statuses

Purpose This study aims to investigate the effects of exhaust direction on exhaust plume and helicopter infrared radiation in hover and cruise status. Design/methodology/approach Four exhaust modes are concerned, and the external flow field and fuselage temperature field are calculated by numerical simulation. The infrared radiation intensity distributions of the four models in hovering and cruising states are computed by the ray-tracing method. Findings Under the hover status, the exhaust plume is deflected to flow downward after it exhausts from the nozzle exit, upon the impact of the main-rotor downwash. Besides, the exhaust plume shows a “swirling” movement following the main-rotor rotational direction. The forward-flight flow helps prevent the hot exhaust plume from a collision with the helicopter fuselage generally for the cruise status. In general, the oblique-upward exhaust mode provides moderate infrared radiation intensities in all of the viewing directions, either under the hover or the cruise status. Compared with the hover status, the infrared radiation intensity distribution alters somewhat in cruise. Originality/value Illustrating the influences of exhaust direction on plume flow and helicopter infrared radiation and the differences of helicopter infrared radiation under hover and cruise statuses are identified. Finally, an appropriate exhaust mode is proposed to provide a better IR signature distribution.